Optical discs and hard disc drives (HDDs) have usually been used as large-capacity storage media. Recently, however, with the development of semiconductor technology, research and development for replacing an HDD with a non-volatile memory module have been performed. More specifically, NAND flash memory is being considered as a memory that can replace an HDD because it has a high degree of integration and has a low cost with respect to its capacity.
When a NAND flash memory module is used in a storage system, the storage system uses a plurality of NAND flash memory modules. At this time, a system maker or provider usually stores system software (S/W), such as an operating system (OS) and critical application programs, that is essential to system operation in one of the plurality of flash memory modules when manufacturing the storage system. The memory modules other than the memory module storing the system S/W are used to extend the memory capacity of the system. Because the form factors of all memory modules are the same, however, it is highly likely for users to erroneously move the memory module that stores the system S/W or to misuse it.
FIG. 1 is a schematic diagram illustrating a conventional NAND flash memory module system 100. The conventional NAND flash memory module system 100 includes a memory controller 110, a plurality of memory modules 121, 122, 123, and 124, and a plurality of sockets 131, 132, 133, and 134. Each of the memory modules 121 through 124 includes a plurality of NAND flash memory chips MC, each of which is connected with the memory controller 110 via a signal line 140 connecting the sockets 131 through 134 with the memory controller 110. There may be more or less memory modules than the four that are shown.
Typically, the form factors of the four memory modules 121 through 124 are the same. The conventional memory modules 121 through 124 usually include one or more notches in order to prevent the user from misinserting a module. These notches are made in the same standard (for example, they have the same size and the same shape) in all of the memory modules 121 through 124. A notch fits with only a corresponding notch coupler and may be referred to as a physical or mechanical key for preventing misinsertion. The sockets 131 through 134 are also all the same. In other words, the sockets 131 through 134 have the same form factors and have the notch couplers following the same standard.
Users can purchase and use additional NAND flash memory modules in order to extend the memory storage capacity. In this case, there is a possibility that a memory module is not inserted into a proper socket since the form factors of all sockets are the same. In addition, no alarm or warning is given when a user removes a memory module storing the system S/W from the proper socket in the conventional technology and, therefore, the memory module storing the system S/W may be lost or inserted into a wrong socket.
In addition, according to the conventional technology, a separate NOR flash memory for storing a boot code or a boot loader for system booting is installed on a system mother board or a NAND flash memory storing the boot code is used as a memory array for a memory module, which makes the system mother board complex and increases manufacturing cost.